Drawing upon decades of experience, RAND provides research services, systematic analysis, and innovative thinking to a global clientele that includes government agencies, foundations, and private-sector firms.

The Pardee RAND Graduate School (PRGS.edu) is the largest public policy Ph.D. program in the nation and the only program based at an independent public policy research organization—the RAND Corporation.

On Distributed Communications Series

XI. Summary Overview

The system uses automatic learning to obtain "perfect switching"[1] in its fully-distributed network
con-figuration. Thus, it is less vulnerable to enemy attack than conventional
networks. (ODC-I, -II, -III)

The system has been designed completely from scratch to meet future
requirements of military security, physical survivability, digital data
flexibility, and ease of adding new services. (ODC-I, -IV, -V, -VIII, -IX)

The system handles start-stop teletype, as well as standard
"high-speed" binary-stream synchronous data rates of 600, 2400, 4800,
9600, and 19,800 bits/sec. It could easily be adapted to handle
very-high-speed data, if required. (ODC-VIII)

Each of the up to 1024 Multiplexing Stations simultaneously handles some
128
cryptographically-secure telephone subscribers, together with 866 other
simultaneous subscribers using other data input devices. (ODC-VIII, -IX)

User-to-user information flows through the network only during actual
transmission of information. For example, after a "pseudo-circuit" is established,
blank spots lasting longer than 1/20 sec in speech modes are not transmitted.
Thus, high-quality speech need only load the transmission plant to an average
equivalent data rate of about 5000 bits/sec. (ODC-VIII)

The system is readily amenable to the use of satellites as links.
(ODC-VII)

The system is able to withstand heavy network damage without interruption
of
on-going, end-to-end traffic. (ODC-I, -II, -III, -IX)

From the user's viewpoint, the system appears to be virtually noise- and
error-free when handling data. (ODC-VIII, -IX)

The network is designed to handle a broad mixture of input/output
devices.
(ODC-III, -VIII, -IX)

Automatic error detection and repeat transmission is built into the
system
on a link-by-link basis, simplifying the design of highly automated, low-cost
digital input devices. (ODC-I, -VII)

Multi-level cryptography and automatic errortracking procedures make the
system far more immune to sophisticated sabotage than any other known
communications system. (ODC-VII, -VIII, -IX)

Instantaneous, multi-station, cryptographicallysecure conference calls
can
be set up even after the conversation is underway. (ODC-VIII)

The potentially high degree of security protection provided permits a
mixing of classified and unclassified traffic, both military and civilian, over
the same facilities. (ODC-VII, -VIII, -IX)

As Message Blocks usually travel by different routes, it appears
impossible
for an eavesdropper to decrypt traffic unless all preceding Message Blocks are
received. (ODC-II, -III, -VIII, -IX)

The system appears to be highly resistant to overload--even when
subjected
to heavy damage. (ODC-V)

The overall system reliability offers hopes of being far better than
today's systems; and, it can be built of elements of lower-reliability than
presently used. (ODC-I, -III, -VII, -X)

The system uses regenerative (saturated) amplification to circumvent the
effects of cumulative distortion, thereby permitting the use of inexpensive,
high-data-rate links. (ODC-VIII, -X)

The system uses the "mini-cost" microwave to build new high-data-rate
links
at very low cost; 4.5-megabit/sec rates appear feasible at a link cost a
decimal order of magnitude lower than in conventional systems. (ODC-VI)

Cost, even on a per-subscriber basis, appears roughly comparable to that
of
present-day conventional networks. (ODC-VIII, -X)

Signaling symbols are transmitted as repetitive binary patterns at the
same
bit rate as the data information, permitting additional signaling, if desired,
while the receiver is "off-hook." This feature can be used to
simplify future automatic computer-to-computer conversation. (ODC-VIII)

Automatic error detection and analysis is easily implemented by virtue of
the all-digital nature of the equipment, facilitating the locating of possible
sources of trouble. (ODC-VII, -IX)

This system has the security, speed, and low-error characteristics to
make
it useful as a signaling network to set circuit switches for possible
extremely-high-data-rate circuit-switched systems in the far future.

Explore

The RAND Corporation is a research organization that develops solutions to public policy challenges to help make communities throughout the world safer and more secure, healthier and more prosperous. RAND is nonprofit, nonpartisan, and committed to the public interest.